1. Field of the Invention
The invention relates to an elevation apparatus for a device such as an office chair, a leg of a table or things like that. More particularly, this invention relates to a pneumatic lift apparatus to hold a device, such as an office chair, a leg of a table or things like that, for a user to use while either sitting at the device or standing near the device.
2. Description of the Related Art
Pneumatic lift apparatus are usually adapted for elevation adjustment of a device such as an office chair, a leg of a table or things like that. A prior pneumatic lift apparatus as disclosed in Taiwan Patent No 579776 comprises a main body and an outer tube, with both the cross-section of the main body and the outer tube being a perfect circle. The main body is rotably received in the outer tube, so that the device connected to the main body can be driven to rotate. However, such pneumatic lift apparatus is not suitable for use with a device (such as an office chair or leg of a table or things like that) which is not rotatable. Therefore, another pneumatic lift apparatus comprises a main body and an outer tube, with both the cross-section of the main body and the outer tube being polygonal. Nevertheless, an expensive manufacturing process of the polygonal main body and outer tube is still one of the problems.
Therefore, the present invention is intended to obviate or at least alleviate the problems encountered in the prior art.